This invention relates to a needle for a tufting machine and more particularly to a needle wherein the shank or mounting portion thereof is offset from the blade of the needle so that the yarn guide groove that extends along the blade from the eye opens at a mouth which is in line with the groove and does not intersect the shank.
Needles for a tufting machine are well known. See for example U.S. Pat. Nos. 3,954,072 and 4,194,457, and German Patent No. 3,545,692. Such needles are used mainly in machines which manufacture floor coverings such as carpet. In such needles, in order to thread the yarn into the eye of the needle, it is necessary for yarn to be fed into an elongated yarn feed or guide groove in the needle body, the yarn passing down the groove and into the eye of the needle. With these known needles, the top of the yarn guide groove opens onto the side of the needle body which necessitates yarn being fed into the groove at an angle. Due to this angular feed of yarn into the yarn feed groove, during piercing of the backing material by the needle during operation of the tufting machine, the yarn can be damaged either because it is not lying correctly or completely in the yarn guide groove which can cause the yarn to be crushed between the needle body and the backing material during piercing of the backing material by the needle. This is particularly a problem where the backing material is relatively hard. A further consequence of the yarn not being correctly in the yarn feed groove is that the hole punctured in the backing material can be elongated by the yarn which results in a detraction of the appearance of the finished tufted fabric. Furthermore, problems may also arise due to backstitch retention, variation of the level of tufts in loop or cut pile, both of which also lead to a detraction in appearance in the finished fabric.
In order to alleviate this problem, a tufting needle has been proposed in the prior art in which a top part of the needle is generally offset from and substantially parallel to the needle body, and in the region of this offset, a second eye of the needle is formed, as an extension of the yarn guide groove formed in the needle body. This additional eye of the needle in conjunction with the yarn guide groove and the eye of the needle permits good guidance of yarn, but experience has shown that due to the weakening of the material of the needle by the presence of the second eye, there is a greater likelihood of needle breakage in this region of the needle. A further problem with a double-eyed needle of this type is that it can be extremely difficult to thread when used in a fine gauge configuration and almost impossible to thread when a staggered needle arrangement is used. A still further problem arises due to the elongation of the punctured hole in the backing material since this can give rise to a weakening of the tufted fabric. This can particularly give rise to problems when, for example, the tufted fabric is required to be molded, such as in the automobile industry.